By using the transaction identifier provided by （） for a particular row change， you can use the Flashback Transaction Query to see the operation performed by the transaction. 

单项选择题You executed the following query：  SELECT operation， undo_sql， table_name  FROM flashback_transaction_query  Which statement is correct regarding the query output？（）

A.It would return information regarding only the last committed transaction.
B.It would return only the active transactions in all the undo segments in the database.
C.It would return only the committed transactions in all the undo segments in the database. 
D.It would return both active and committed transactions in all the undo segments in the database.
E.It would return information regarding the transactions that began and were committed in the last 30 minutes.

单项选择题By mistake， you ran the batch job （for updating the BILL_DETAILS table） twice. You are not sure which rows in the BILL_DETAILS table were affected. You need to identify：  a） a list of changes made along with the transaction identifier of each change  b） the necessary SQL statements to undo the erroneous changes  Which option would you choose？（）

A.RMAN only
B.Flashback Table only
C.Flashback Versions Query only
D.Flashback Database and Flashback Transaction Query
E.Flashback Versions Query and Flashback Transaction Query

单项选择题You are working in an online transaction processing （OLTP） environment. You realize that the salary for an employee， John， has been accidentally modified in the EMPLOYEES table. Two days ago， the data was in the correct state. Flashback logs generated during last two days are available in the flash recovery area.  Which option would you choose to bring the data to the correct state while ensuring that no other data in the same table is affected？（）

A.perform point­in­time recovery
B.perform a Flashback Table operation to restore the table to the state it was in two days ago 
C.perform a Flashback Database operation to restore the database to the state it was in two days ago
D.perform Flashback Versions Query and Flashback Transaction Query to determine all the necessary undo SQL statements， and then use them for recovery

单项选择题Why would you use the following FLASHBACK TABLE command？（） FLASHBACK TABLE emp TO TIMESTAMP （’11：45’，’hh12：mi’）

A.to undo the changes made to the EMP table since the specified time
B.to restore the EMP table that was wrongly dropped from the database
C.to view the transactions that have modified the EMP table since the specified time
D.to view the changes made to the EMP table for one or more rows since the specified time
E.to recover the EMP table to a point in time in the past by restoring the most recent backup

多项选择题YouexecutedthefollowingFLASHBACKTABLEcommand：FLASHBACKTABLEempTOTIMESTAMP（’11：45’，’hh12：mi’）Whichtwostatementsarecorrect？（）

A.The FLASHBACK TABLE statement will not be written to the alert log file.
B.The changes made to the EMP table since the specified time will be undone.
C.The EMP table that was dropped by mistake from the database will be restored.
D.The FLASHBACK TABLE statement will be executed within a single transaction.
E.The FLASHBACK TABLE statement will not maintain the existing indexes on the EMP table. 
F.The list of transactions that have modified the EMP table since the specified time will be displayed.